Psychiatric Symptoms Associated with Non-Celiac Gluten Sensitivity: A Focused Narrative Review

Non-celiac gluten sensitivity (NCGS), even though it is a term defined for more than four decades, is still an enigmatic clinical entity. This is primarily due to the absence of specific diagnostic criteria, with most reports relying on patients' self-diagnosis. Individuals with NCGS experience intestinal (abdominal pain, bloating, diarrhea, or constipation) and extraintestinal symptoms ("foggy mind," depression, anxiety, and deterioration of psychiatric conditions) after gluten consumption. Frequent disregard and oversight of extraintestinal manifestations, such as psychiatric symptoms, further complicates NCGS. The lack of understanding about NCGS causes individuals living with this condition to experience distress, frustration, and stigmatization. An impaired intestinal barrier, gut dysbiosis, and alterations in the gut-brain axis are proposed as key factors in the NCGS and psychiatric symptoms associated with NCGS. None of these links are yet definitive, and the methodological limitations of existing studies-small samples, self-reported diagnoses, and insufficient blinding-demand that conclusions be drawn with appropriate restraint. The purpose of this review is to provide an up-to-date understanding of the pathophysiology of NCGS and psychiatric symptoms associated with NCGS. Future studies should focus on development of reliable, objective diagnostic markers for NCGS and on the design of adequately powered, double-blind, placebo-controlled trials that incorporate validated psychiatric outcome measures alongside intestinal indices.